The present invention is directed to a central call-processing system for a cellular or cellular-like telephone system.
The increasing availability of mobile and portable communications over the past decade has freed business and residential users from the physical constraints of a wholly wired telecommunications network. Cellular communications systems, together with paging and other complementary services, has brought mobility to telecommunications services for the first time. Significant technical advances in mobile and portable technologies, as well as in new technologies such as digital transmission with respect to wireless telecommunications, have substantially expanded the number and types of wireless telecommunications services using the cellular spectrum that can be made available to the user. These prospective services include, but are not limited to, advanced forms of cellular telephone service, advanced digital cordless telephone service, portable facsimile services, wireless private branch exchange services, and wireless local area network services, and may be used through the existing public switched network or through alternative local wired networks (such as cable television systems). As such, digital personal communications systems can exist independently of local wired networks, filling gaps that are existing in current communications systems, and also in creating new markets many yet to be defined. Accordingly, providers of cellular systems, including Personal Communication Systems (PCS), will have the ability to reach and serve existing and new markets, both nationally and globally, in an economic and responsive manner. According to the invention, it is advantageous to construct a hybrid cellular system, that may include a PCS, that is fully compatible with any and all open network interface requirements that may currently exist, or are expected to exist in the future, such that a number of different, hithertofore incompatible cellular systems may be linked together by means of one central processor using multiple common air-interface protocols. Thus, for example, a provider of an Advanced Mobile Phone Service (AMPS) analog cellular phone system, with its one or more base stations and local cellular customers, may be directly and wirelessly linked, for example, to a provider of the Global System for Mobile Communications (GSM) digital cellular system, or, either or both of the above may be linked to a provider of the Nordic Mobile Telephone (NMT) 450 Mhz.-frequency cellular system, or to a provider of the Extended Total Access Cellular System (E-TACS).
Each of the above-mentioned cellular systems has its own specifications and protocols that have hithertofore prevented ready and easy coupling of one system with another system, which has prevented a cellular call from one type of system to be made to another type of system without having to be first routed through the public switched telephone network (PSTN).
Traditional, wireless communication systems, such as those named above, typically implement the call-control and real-time operational activities in the actual switching exchange equipment connected to the PSTN, while all other activities are handled in an external, dedicated, adjunct platform computer. Such systems must route their calls through the PSTN, if a call is being made to another type of cellular system, as above-described. Since the call-control and real-time operational activities are embedded in the actual switching exchange equipment, any upgrade or change to the system is considerably time-consuming and costly, often necessitating replacement of switching equipment hardware.
Owing to the fact that conventional cellular systems require such switching-equipment control, such systems require very complicated and decentralized billing schemes. These prior-art systems rely on external billing computer platforms to process call detailing information. This information is typically downloaded only once or twice a month to the cellular provider. Therefore, the time period between a placement of a call and the time that the call is billed may be a month or so, often allowing a subscriber to surpass his prescribed monthly call-limit.
Traditional cellular systems require separate and specific processing platforms to support the mobility and network administration functions of the system, and thus require duplication of such platforms to provide back-up capability.